Synthesis method and application of H-type high-silicon-wafer-shaped MOR zeolite molecular sieve

Abstract

The invention provides a synthesis method and application of an H-type high-silicon-wafer-shaped MOR zeolite molecular sieve, and belongs to the technical field of synthesis and application of molecular sieves. The method comprises the following steps: adding an aluminum source into a mixed solution containing an alkali source, tetraethylammonium hydroxide, long-chain bipiperidine onium salt and water to form slurry, adding a silicon source and a small-grain MOR zeolite molecular sieve seed crystal into the slurry, uniformly mixing to obtain silicon-aluminum sol, aging the silicon-aluminum sol, carrying out a crystallization synthesis reaction, carrying out ammonium ion exchange on the obtained crystallization product, and drying to obtain the small-grain MOR zeolite molecular sieve. And filtering, washing, drying and roasting to obtain the H-type high-silicon-wafer-shaped MOR zeolite molecular sieve. According to the molecular sieve synthesized by the invention, the Al element is enriched in an eight-membered ring of an MOR zeolite molecular sieve skeleton structure, the quantity of B acid in the eight-membered ring is increased, and the molecular sieve has a small-grain morphology feature structure, can effectively shield acid sites in side reaction in HMOR, is applied to a reaction for synthesizing methyl acetate by carbonylation of dimethyl ether, and has a good application prospect. The catalyst has the advantages of high catalytic activity, good product selectivity, simple preparation process and easy industrial amplification.

Description

TECHNICAL FIELD

[0001] The present application relates to a synthesis method and application of H-type high-silicon sheet-like MOR zeolite molecular sieve, in particular to a process of preparing a catalyst from a hydrogen-type high-silicon sheet-like MOR molecular sieve and applying the catalyst to a dimethyl ether or methanol carbonylation reaction to produce methyl acetate, and belongs to the technical field of molecular sieve synthesis and application. BACKGROUND

[0002] In the dimethyl ether carbonylation reaction, although the H-type mordenite (HMOR) molecular sieve has unique pore structure, large specific surface area and strong acidity, etc., it still faces serious problems in practical application. The length of the molecular sieve channel significantly hinders the diffusion of raw materials and product molecules, leading to the accumulation of large molecular products (such as carbon deposition) in the channel, which enhances the rate of carbon deposition and further causes the rapid deactivation of the molecular sieve. At the same time, a large number of secondary reactions occur in the channel, which leads to a sharp decrease in reaction selectivity and affects the generation efficiency of the target product methyl acetate. As an important organic raw material intermediate, methyl acetate is widely used in the textile, perfume and pharmaceutical industries, so the catalyst deactivation and selectivity decline directly restrict its industrial application value.

[0003] Mordenite (MOR) is a one-dimensional large-pore zeolite with a framework composed of 12-membered ring (0.65 x 0.70 nm) and 8-membered ring (0.26 x 0.57 nm) channels along the c-axis direction, connected by 8-membered ring side pockets (0.34 x 0.48 nm). Studies have shown that the active center of dimethyl ether carbonylation reaction is located at the B acid site of the 8-membered ring, while the active site of the 12-membered ring is related to the deactivation of the zeolite. Specifically, the length of the c-axis of mordenite has an important influence on the reaction activity: although a longer c-axis can enrich CO and promote the carbonylation reaction, it is also prone to cause carbon deposition and catalyst deactivation. In addition, due to the narrow 8-membered ring channel along the c-axis direction, molecular diffusion is limited, making mordenite often exhibit one-dimensional channel characteristics in actual catalysis, further exacerbating the diffusion problem and deactivation phenomenon. Researchers have proposed strategies to synthesize nanoscale flake-shaped zeolites to shorten the channel length and enhance molecular diffusion. Specific methods include: using a double-template method or specific organic templates (such as double-headed quaternary ammonium salts, long-chain single-headed quaternary amines, etc.), through the synergistic effect or selective adsorption effect between templates, the growth direction of mordenite crystals is regulated, forming flake structures along the c-axis or b-axis. For example: literature (J. Mater. Chem. A, 2017, 5, 8887-8891) used long-chain single-headed quaternary amine to synthesize mordenite with a thickness of 20-40 nm along the c-axis. Patent CN107963637A used hexadecyl N-dimethyl ethyl-N, N dimethyl ammonium bromide as a template to synthesize flake-shaped mordenite with a c-axis thickness of 40 nm. Literature (Angew. Chem. Int. Ed. 2020, 59, 6258-6262) used hexadecyl N dimethyl butyl N dimethyl benzyl amine as a template to synthesize flake-shaped mordenite with a thickness of 11 nm along the b-axis. Through low-pressure SiCl4 treatment (LPST), the proportion of framework aluminum in T3 sites is increased, and the catalytic performance is optimized. The introduction of additives: the introduction of specific molecules or ions (such as boric acid, KOH) can replace the position of aluminum or change the alkalinity, control the oriented growth of mordenite, and form flake-shaped crystals. These methods simplify the synthesis steps and effectively control the thickness and layer spacing of the flake. By directly synthesizing flake-shaped mordenite, it is expected to significantly improve the catalytic performance: the flake structure effectively shortens the length of the twelve-membered ring and eight-membered ring channels, greatly enhances the diffusion ability of raw material and product molecules, and reduces carbon deposition and secondary reactions. Flake-shaped mordenite exhibits better catalytic activity than traditional mordenite in dimethyl ether carbonylation reaction due to the high catalytic rate and good diffusion of the 8-MR side pocket acid center, with methyl acetate selectivity exceeding 99%, and significantly extending the catalytic life. Theoretical calculations show that the flake structure is stable and suitable for carbonylation, cyclization, and methanol-to-olefins (MTO) and other catalytic reactions.

[0004] However, in the above technical solutions, the synthesis method depends on a large number of complex and expensive organic structure directing agents, which increases the production cost and limits large-scale industrial application. In addition, the synthesized nanosheet MOR molecular sieve has a difficult-to-adjust silicon-aluminum ratio in a wide range, and the acid site distribution is not optimal, which requires complex post-processing. Direct synthesis of a mordenite with ideal nanomorphology and optimal acid site distribution is a major challenge that has not yet been solved. SUMMARY

[0005] The present application aims to overcome the deficiencies of the prior art, and directly synthesizes high-silicon sheet MOR zeolite molecular sieve by using a relatively small amount of long-chain dipiperidinium salt organic matter as an organic structure aid and combining with tetraethylammonium hydroxide as a main template agent, so as to enrich Al elements in the MOR zeolite molecular sieve structure octal ring, increase the number of B acid in the octal ring, and prepare HMOR zeolite molecular sieve with small grain morphology characteristic structure. When applied to the synthesis of methyl acetate by dimethyl ether carbonylation, the prepared HMOR zeolite molecular sieve has high catalytic activity, good product selectivity, simple preparation process and easy industrial amplification.

[0006] The present application uses TEAOH compound as an organic template agent and long-chain dipiperidinium salt organic matter as a crystallization aid, which is beneficial to the synthesis of sheet MOR zeolite molecular sieve, improves the kinetic diffusion effect of reaction molecules, improves the reaction stability, reduces irreversible adsorption, and prolongs the service life of the molecular sieve catalyst.

[0007] The present application provides a synthesis method of H-type high-silicon sheet MOR zeolite molecular sieve, which comprises: (1) adding an aluminum source to a mixed solution containing an alkali source, tetraethylammonium hydroxide, long-chain dipiperidinium salt and water to form a slurry, adding a silicon source and small-grain MOR zeolite molecular sieve seeds to the slurry, and uniformly mixing to obtain a silicon-aluminum sol; (2) after aging treatment of the silicon-aluminum sol, performing a crystallization synthesis reaction, and performing ammonium ion exchange on the obtained crystallization product, filtering, washing, drying and calcining to obtain H-type high-silicon sheet MOR zeolite molecular sieve.

[0008] Further, the long-chain dipiperidinium salt is at least one selected from 1,1'-(1,6-hexanediyl)bis[1-methyl-diodopiperidinium], 1,1'-(oxydi-2,1-ethanediyl)bis[1-ethyl-dibromopiperidinium], 1,1'-(thio-2,1-ethanediyl)bis[1-methyl-dichloropiperidinium], 1,1'- (1,10-decanediyl)bis[1-methyl-diodopiperidinium], and 1,1'-[1,4-phenylenebis(methylene)]bis[1-ethyl-dibromopiperidinium].

[0009] Further, in the silica-alumina sol, the molar ratio of each component is 0.04-0.15 Na2O:SiO2:0.02-0.08 Al2O3:0.01-0.5 TEA2O:0.02-0.25 PIPD:8-40 H2O, calculated as Na2O for the alkali source, SiO2 for the silicon source, Al2O3 for the aluminum source, TEA2O for the tetraethylammonium hydroxide, and PIPD for the long-chain dipicrydinium salt; and the addition amount of the small-grained MOR zeolite molecular sieve seed is 1wt%-10wt% of the mass of SiO2.

[0010] Further, the addition amount of the small-grained MOR zeolite molecular sieve seed is 1wt%-5wt% of the mass of SiO2.

[0011] Further, the temperature of the aging treatment is 40-130℃, and the time of the aging treatment is 12-72 hours.

[0012] Further, the temperature of the aging treatment is 80-120℃, and the time of the aging treatment is 12-48 hours.

[0013] Further, the temperature of the crystallization synthesis reaction is 140-200℃, and the time of the crystallization synthesis reaction is 12-72 hours.

[0014] Further, the temperature of the crystallization synthesis reaction is 180-200℃, and the time of the crystallization synthesis reaction is 12-48 hours.

[0015] Further, after the slurry after the crystallization synthesis reaction is washed to a pH of 7-8, the slurry is dried at 100-120℃ for 4-12h, heated to 450-650℃ at a heating rate of 1-5℃ / min, and calcined for 4-12h to obtain a molecular sieve raw powder.

[0016] Further, the ammonium exchange is carried out by mixing the calcined molecular sieve raw powder with a water-soluble ammonium salt solution at a solid-liquid mass ratio of 1:(5-30) at 60-90℃ for 1-6h, and repeating the exchange 1-3 times. The concentration of the water-soluble ammonium salt solution is 0.1-1.0 mol / L, and the water-soluble ammonium salt is at least one selected from the group consisting of ammonium nitrate, ammonium chloride, ammonium sulfate, ammonium carbonate, ammonium bicarbonate, and ammonium acetate.

[0017] Further, after the ammonium exchange, the mixture is dried and calcined, the temperature of the drying is 80-150℃, the time of the drying is 2-24h, the temperature of the calcination is 450-600℃, and the time of the calcination is 1-12h.

[0018] Further, the silicon source is selected from at least one of silica sol, water glass, white carbon black, C-type silica gel, fumed silica, chromatographic silica gel, methyl orthosilicate and ethyl orthosilicate; the aluminum source is selected from at least one of sodium aluminate, sodium metaaluminate, aluminum hydroxide, pseudo-boehmite, aluminum nitrate, aluminum chloride, aluminum powder, aluminum isopropyl alcohol and aluminum sulfate; and the alkali source is selected from at least one of NaOH, Na2O, Na2O2, Na2CO3 and metallic Na.

[0019] The application further provides the H-type high-silicon sheet-like MOR zeolite molecular sieve prepared by the above synthesis method, wherein the H-type high-silicon sheet-like MOR zeolite molecular sieve has a Si / Al molar ratio of 30:1 to 5:1, and a c-axis direction thickness of less than 200 nm.

[0020] Further, the H-type high-silicon sheet-like MOR zeolite molecular sieve has a Si / Al molar ratio of 20:1 to 7:1, and a c-axis direction thickness of less than or equal to 100 nm.

[0021] The application further provides application of the H-type high-silicon sheet-like MOR zeolite molecular sieve in preparation of methyl acetate in a carbonylation reaction.

[0022] Further, raw material gas containing dimethyl ether, carbon monoxide and hydrogen is reacted to synthesize methyl acetate by passing through a catalyst bed loaded with the H-type high-silicon sheet-like MOR zeolite molecular sieve, wherein the reaction temperature is 180 to 280℃, the reaction pressure is 0.5 to 6.0 Mpa, and the gas volume space velocity is 1000 to 6000 mL / (gcat•h). In the raw material gas, the molar ratio of dimethyl ether, carbon monoxide and hydrogen is 1:(4 to 10):(3 to 15), and dry inert gas is used as pretreatment gas.

[0023] Further, the reaction temperature is 180 to 240℃, the reaction pressure is 2.0 to 5.0 Mpa, and the gas volume space velocity is 1500 to 4000 mL / (gcat•h).

[0024] The application can produce at least the following beneficial effects, but is not limited to the following aspects: Because the auxiliary agent molecule contains two positively charged piperidinium cations (six-membered ring), through a rigid long alkyl chain (usually methylene chain -(CH2) nThe connection, the geometry of the whole molecule is relatively fixed, can accurately match the size and shape of the target molecular sieve channel, so the present application can stably synthesize a sheet-shaped MOR zeolite molecular sieve with reduced length in the c-axis direction, reduce the diffusion of reaction molecules and product molecules, reduce the probability of side reactions, and improve the conversion efficiency.

[0025] 2) The present application can directionally regulate the acid distribution of the HMOR molecular channel, selectively reduce the concentration of the acid sites in the twelve-membered ring, effectively shield the acid sites in the HMOR where side reactions occur, increase the concentration of the acid active sites in the eight-membered ring, and can significantly improve the conversion rate and catalytic life of the HMOR catalyzed dimethyl ether carbonylation at the same time.

[0026] 3) The mordenite molecular sieve provided by the present application has good reproducibility in the synthesis process, high product purity, and a corresponding catalyst preparation method that is simple in process and conducive to large-scale industrial production, improves the conversion rate of dimethyl ether on the basis of maintaining high selectivity.

[0027] 4) The present application provides a dimethyl ether production methyl acetate catalyst, which has high activity, high space-time yield of methyl acetate, and good stability, can not only ensure high product yield and long service life, but also has a wide range of adjustable reaction process conditions, making the present application have universality and have a very wide range of industrial applications. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 XRD diffraction pattern of the MOR zeolite HMR-1 sample synthesized in Example 1.

[0029] Figure 2 XRD diffraction pattern of the MOR zeolite HMR-2 sample synthesized in Example 2.

[0030] Figure 3 XRD diffraction pattern of the MOR zeolite HMR-3 sample synthesized in Example 3.

[0031] Figure 4 SEM morphology diagram of the MOR zeolite HMR-1 sample synthesized in Example 1.

[0032] Figure 5 SEM morphology diagram of the MOR zeolite HMR-2 sample synthesized in Example 2.

[0033] Figure 6 SEM morphology diagram of the MOR zeolite HMR-3 sample synthesized in Example 3. DETAILED DESCRIPTION

[0034] The embodiments of the present application and the effects produced thereby are further illustrated by the examples and comparative examples, but the scope of protection of the present application is not limited to the contents listed in the examples.

[0035] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not critical to the properties. The endpoints of the ranges and any values are provided as approximations only, and are understood to include values near the recited endpoints. The endpoints of the ranges of values (as well as the values themselves) can be combined with one or more of the other endpoints to recite one or more new ranges of values.

[0036] In the present embodiment, the sample was characterized by XRD using a PANalytical model X pert Pro diffractometer, Cu Kα ray (λ = 0.15406 nm), tube voltage 45 kV, tube current 40 mA, scanning range 5°-55°, step 0.026°, 17.34 ms per 1 step. According to the five highest characteristic peaks at 2θ = 9.8 ± 0.1°, 19.6 ± 0.1°, 22.3 ± 0.1°, 25.7 ± 0.1° and 26.3° ± 0.1°, corresponding to (200), (330), (150), (202) and (350) crystal faces, the sum of XRD diffraction peak areas was used to calculate the relative crystallinity.

[0037] The sample was detected by a HITACHI thermal field emission scanning electron microscope SU5000 in a backscattering mode, the beam current was adjusted to "standard", the acceleration voltage was selected to be 10 kV, and the magnification was 5k-50k.

[0038] In the present embodiment, a Thermo Scientific Nicolet 6700 was used for in-situ infrared, and the specific procedure was as follows: degassing at 450°C under a vacuum atmosphere for 60 min, after cooling to 150°C, 10% NH3 / Ar mixed gas was introduced, and after adsorption saturation, vacuum was extracted for 30 min to remove gaseous and physically adsorbed ammonia molecules, and the spectrum was recorded. The number of total B acid in the sample can be calculated according to the peak intensity at 1540 cm -1 The number of B acid in the twelve-membered ring of the molecular sieve was characterized by pyridine adsorption infrared, and the specific procedure was as follows: degassing at 450°C under a vacuum atmosphere for 30 min, after cooling to 150°C, saturated pyridine vapor was introduced, and after static adsorption saturation, vacuum was extracted for 30 min to remove gaseous and physically adsorbed pyridine molecules, and the spectrum was recorded. The number of B acid in the twelve-membered ring of the sample can be calculated according to the peak area at 1540 cm -1 (Applied Catalysis A: General 417-418 (2012) 236-242). Finally, the number of B acid in the eight-membered ring was obtained by subtracting the number of B acid in the twelve-membered ring from the total number of B acid.

[0039] The raw materials in the embodiments of the present application are all purchased through commercial channels without any special treatment and are directly used without special treatment, unless otherwise specified. The seed crystals described in the embodiments of the present application are small-grained MOR zeolite molecular sieves synthesized without a template agent and commercially available. Example 1

[0040] 1) 36.49 g of deionized water, 0.08 g of NaOH (purity 99%) and 1.91 g of sodium metaaluminate (Na2O content: 30.62 wt%, Al2O3 content: 38.50% wt%) were mixed into a uniform solution, and then stirred for 30 min. Then, 22.09 g of TEAOH solution (content 25%, denoted as TEA2O) and 27.09 g of 1,1'-(1,6-hexanediyl)bis[1-methyl-diiodonium piperidinium] (purity 99%, denoted as PIPD) were added, followed by adding 51.46 g of silica sol (SiO2 content: 29.19 wt%, Na2O content: 0.07 wt%) to the above mixed solution, and then adding 0.30 g of small-grained MOR zeolite molecular sieve seed crystals, and stirring at room temperature for 30 min to obtain a crystallization slurry precursor, the component molar ratio of which is: 0.047 Na2O: SiO2: 0.02878 Al2O3: 0.15 TEA2O: 0.2 PIPD: 20 H2O, and the amount of the seed crystals added is 2% of the total weight of SiO2 in the synthesis slurry.

[0041] 2) The gelled slurry was transferred into the inner container of a hydrothermal crystallization kettle, and was placed in a constant-temperature oven for static aging at 100°C for 12 h, and then was heated to 190°C for dynamic crystallization for 18 h. After the hydrothermal crystallization was completed, the product slurry was taken out and was subjected to suction filtration, and the filter cake obtained after repeated washing with deionized water was repeatedly washed with deionized water and was then dried in a 120°C oven for 8 h, and was calcined in a muffle furnace at 550°C (3°C / min heating) for 4 h, to obtain a Na-type MOR zeolite molecular sieve, the silicon-aluminum ratio nSiO2 / nAl2O3 of which is 29.65, and the relative crystallinity of which is 100%.

[0042] 3) The Na-type MOR zeolite molecular sieve sample powder was dissolved in a 0.5 mol / L ammonium nitrate solution, and was subjected to ion exchange at a solid-liquid mass ratio of 1:25 at a temperature of 80°C for 3 h, and the operation was repeated twice, to obtain an NH4-type MOR, which was recovered after filtration and drying, and was then calcined in a muffle furnace at 500°C for 4 h, to obtain an H-type MOR, which is denoted as HMR-1. Example 2

[0043] 1) 12.73 g of deionized water, 0.32 g of Na2O2 (purity 99%) and 0.90 g of pseudoboehmite (Al2O3 content: 78 wt%) were mixed into a homogeneous solution, and stirring was continued for 30 min, then 50.80 g of TEAOH solution (content 25%, marked as TEA2O) and 7.13 g of 1,1'-(oxydi-2,1-ethanediyl)bis[1-ethyl-dibromopiperidinium] (purity 99%, marked as PIPD) were added, followed by 24.74 g of water glass (SiO2 content: 29.92 wt%, Na2O content: 10.76 wt%) and 38.04 g of silica sol (SiO2 content: 29.19 wt%, Na2O content: 0.07 wt%) added to the above mixed solution, 0.37 g of small crystal MOR zeolite molecular sieve seeds were added, and the mixture was stirred vigorously at room temperature for 30 min to obtain a crystallization slurry precursor, the molar ratio of the components was: 0.156 Na2O: SiO2: 0.0224 Al2O3: 0.28 TEA2O: 0.05 PIPD: 16.7 H2O, and the amount of seed added was 5% of the total weight of SiO2 in the synthesis slurry.

[0044] 2) The gel slurry was transferred to the inner container of the hydrothermal crystallization kettle, and was placed in a constant temperature oven for static aging at 80°C for 24 h, and then the temperature was increased to 200°C for dynamic crystallization for 15 h. After the hydrothermal crystallization was completed, the product slurry was removed and was repeatedly washed with deionized water by suction filtration, and the filter cake obtained after repeated washing was placed in a 105°C oven for drying for 12 h, and was calcined in a muffle furnace at 540°C (3°C / min heating) for 6 h, to obtain Na-type MOR zeolite molecular sieve, the silicon-aluminum ratio nSiO2 / nAl2O3 = 39.24, and the relative crystallinity was 101%.

[0045] 3) The Na-type MOR zeolite molecular sieve sample powder was dissolved in a 1.0 mol / L ammonium chloride solution, and was subjected to ion exchange at a solid-liquid mass ratio of 1:10 at a temperature of 90°C for 3 h, and the operation was repeated once, and the obtained NH4-type MOR was recovered by filtration and drying, and was then calcined in a muffle furnace at 550°C for 4 h, to obtain H-type MOR, which was marked as HMR-2. Example 3

[0046] 1) 55.91 g of deionized water, 1.02 g of NaOH (purity 99%), 0.36 g of Na2CO3 (purity 99%) and 1.55 g of aluminum hydroxide (purity 99 wt%) were mixed into a uniform solution, and stirring was continued for 30 min, then 34.22 g of TEAOH solution (content 25%, marked as TEA2O) and 2.25 g of 1,1'-(thio-2,1-ethanediyI) bis[1-methyl-dichloropiperidinium] (purity 99%, marked as PIPD) were added, followed by 10.71 g of white carbon black (SiO2 content: 93.09 wt%) added to the above mixed solution, 0.30 g of small crystal MOR zeolite molecular sieve seed was added, and strong stirring was carried out at room temperature for 30 min to obtain a crystallization slurry precursor, the molar ratio of the components was: 0.103 Na2O: SiO2: 0.03519 Al2O3: 0.35 TEA2O: 0.025 PIPD: 30 H2O, and the amount of seed added was 3% of the total weight of SiO2 in the synthesis slurry.

[0047] 2) The gel slurry was transferred to the inner container of the hydrothermal crystallization kettle, and was placed in a constant temperature oven for static aging at 120°C for 24 hours, and then the temperature was increased to 180°C for dynamic crystallization for 24 h. After the completion of hydrothermal crystallization, the product slurry was taken out and suction filtered, and the filter cake obtained after repeated washing with deionized water was repeatedly suction filtered and then dried at 110°C in an oven for 12 h, and then calcined in a muffle furnace at 500°C (3°C / min heating) for 6 h, to obtain Na-type MOR zeolite molecular sieve, the silicon-aluminum ratio nSiO2 / nAl2O3 = 23.42, and the relative crystallinity was 103%.

[0048] 3) The Na-type MOR zeolite molecular sieve sample powder was dissolved in a 1.5 mol / L ammonium sulfate solution, and ion exchange was carried out at a solid-liquid mass ratio of 1:5 at a temperature of 60°C for 3 h, repeated 2 times, and the obtained NH4-type MOR was recovered after filtration and drying, and then was calcined in a muffle furnace at 520°C for 6 h, to obtain H-type MOR, marked as HMR-3. Example 4

[0049] 1) 68.41 g of deionized water, 0.38 g of NaOH (purity 99%) and 0.79 g of sodium aluminate (Na2O content: 39.38 wt%, Al2O3 content: 49.95 wt%) were mixed into a homogeneous solution, and then stirred for 30 min. 7.21 g of TEAOH solution (content 25%, denoted as TEA2O) and 13.73 g of 1,1'- (1,10-decanediyl) bis[1-methyl-diiodopiperidinium] (purity 99%, denoted as PIPD) were added, and then 10.04 g of C-type silica gel (SiO2 content: 91.54 wt%) was added to the above mixed solution, 0.18 g of small crystal MOR zeolite molecular sieve seed was added, and the mixture was stirred at room temperature for 30 min to obtain a crystallization slurry precursor. The molar ratio of the components was: 0.064 Na2O: SiO2: 0.02541 Al2O3: 0.08 TEA2O: 0.15 PIPD: 35 H2O, and the amount of seed added was 2% of the total weight of SiO2 in the synthesis slurry.

[0050] 2) The gel slurry was transferred to the inner container of the hydrothermal crystallization kettle, and was placed in a constant temperature oven for static aging at 60°C for 48 h, and then was heated to 185°C for dynamic crystallization for 36 h. After the hydrothermal crystallization was completed, the product slurry was taken out and was subjected to suction filtration, and the filter cake obtained after repeated washing with deionized water was repeatedly washed with deionized water and was then dried at 130°C in an oven for 4 h, and was calcined in a muffle furnace at 500°C (3°C / min heating) for 8 h, to obtain Na-type MOR zeolite molecular sieve, the silicon-aluminum ratio nSiO2 / nAl2O3 was 34.36, and the relative crystallinity was 105%.

[0051] 3) The Na-type MOR zeolite molecular sieve sample powder was dissolved in a 1.0 mol / L ammonium nitrate solution, and was subjected to ion exchange at a solid-liquid mass ratio of 1:10 at a temperature of 90°C for 2 h, and the operation was repeated 3 times. The obtained NH4-type MOR was recovered after filtration and drying, and was then calcined in a muffle furnace at 560°C for 4 h, to obtain H-type MOR, which was denoted as HMR-4. Example 5

[0052] 1) 89.03 g of deionized water, 2.24 g of Na2O (purity 99%) and 2.05 g of aluminum isopropoxide (purity 99 wt%) were mixed into a homogeneous solution, and stirring was continued for 30 min, and then 6.80 g of TEAOH solution (content 25%, marked as TEA2O) and 51.19 g of 1,1'-[1,4-phenylenebis(methylene)]bis[1-ethyl-dibromopiperidinium] (purity 99%, marked as PIPD) were added, and then 32.29 g of methyl orthosilicate (purity 99 wt%) was added to the above mixed solution, 1.26 g of small crystal MOR zeolite molecular sieve seeds were added, and the mixture was stirred vigorously at room temperature for 30 min to obtain a crystallization slurry precursor, and the molar ratio of the components was: 0.132 Na2O: SiO2: 0.04726 Al2O3: 0.055 TEA2O: 0.45 PIPD: 25 H2O, and the amount of seed added was 10% of the total weight of SiO2 in the synthesis slurry.

[0053] 2) The gel slurry was transferred to the inner container of the hydrothermal crystallization kettle, and was placed in a constant temperature oven for static aging at 130°C for 24 h, and then the temperature was increased to 190°C for dynamic crystallization for 24 h. After the hydrothermal crystallization was completed, the product slurry was taken out and was subjected to suction filtration, and the filter cake obtained after repeated washing with deionized water was repeatedly suction filtered was placed in a 105°C oven for drying for 12 h, and was calcined in a muffle furnace at 550°C (3°C / min temperature increase) for 6 h, to obtain Na-type MOR zeolite molecular sieve, and the silicon-aluminum ratio nSiO2 / nAl2O3 was 14.86, and the relative crystallinity was 98%.

[0054] 3) The Na-type MOR zeolite molecular sieve sample powder was dissolved in a 0.5 mol / L ammonium chloride solution, and was subjected to ion exchange at a solid-liquid mass ratio of 1:15 at a temperature of 60°C for 3 h, and the operation was repeated twice, and the obtained NH4-type MOR was recovered after filtration and drying, and was calcined in a muffle furnace at 550°C for 6 h, to obtain H-type MOR, which was marked as HMR-5. Example 6

[0055] 1) 55.09 g of deionized water, 0.89 g of NaOH (purity 99%) and 3.73 g of aluminum nitrate (purity 99 wt%) were mixed into a uniform solution, and stirring was continued for 30 min, then 14.73 g of TEAOH solution (25% content, denoted as TEA2O) and 37.92 g of 1,1'-(1,6-hexanediyl)bis[1-methyl-diiodopiperidinium] (purity 99%, denoted as PIPD) were added, and then 42.09 g of tetraethyl orthosilicate (purity 99 wt%) was added to the above mixed solution, 0.96 g of small crystal MOR zeolite molecular sieve seeds were added, and strong stirring was carried out at room temperature for 30 min to obtain a crystallization slurry precursor, and the component molar ratio was: 0.055 Na2O: SiO2: 0.04338 Al2O3: 0.125 TEA2O: 0.35 PIPD: 18.5 H2O, and the amount of seed added was 8% of the total weight of SiO2 in the synthesis slurry.

[0056] 2) The gel slurry was transferred to the inner container of the hydrothermal crystallization kettle, and was placed in a constant temperature oven for static aging at 60°C for 24 h, and then the temperature was increased to 190°C for dynamic crystallization for 20 h. After the completion of hydrothermal crystallization, the product slurry was taken out and suction filtered, and the filter cake obtained after repeated washing with deionized water was repeatedly suction filtered and then was placed in a 125°C oven for drying for 12 h, and was calcined in a muffle furnace at 540°C (3°C / min heating) for 4 h, to obtain a Na-type MOR zeolite molecular sieve, the silicon-aluminum ratio nSiO2 / nAl2O3 was 17.75, and the relative crystallinity was 96%.

[0057] 3) The Na-type MOR zeolite molecular sieve sample powder was dissolved in a 1.0 mol / L ammonium nitrate solution, and ion exchange was carried out at a solid-liquid mass ratio of 1:10 at a temperature of 70°C, for 4 h, and the operation was repeated twice, to obtain an NH4-type MOR, which was recovered after filtration and drying, and was then placed in a muffle furnace for calcination at 550°C for 6 h, to obtain an H-type MOR, which was marked as HMR-6.

[0058] Comparative Example 1 Preparation was carried out according to the method in the patent embodiment 1 of CN114229864B: 1) 1.2 g of NaOH was dissolved in 12 g of deionized water, then 0.22 g of aluminum hydroxide and 0.32 g of boric acid were added to the above solution, and after stirring uniformly, the solution was transferred to a stainless steel reaction kettle and moved into a homogeneous reactor, and dynamic dissolution was carried out at 130°C for 5 h, and after taking out, the solution was cooled to room temperature in tap water, to obtain a uniform transparent solution A; 2) 5 g of 25% tetraethylammonium hydroxide solution was added to 10 g of water, and 12 g of silica sol (SiO2: 40 wt%) silica sol was added dropwise, and stirring was continued for 2 h, to obtain a sol B.

[0059] 3) The sol B was added dropwise into the solution A to form a white gel, and the stirring was kept during the titration, and the stirring was continued for 2 h after the titration was completed. The molar composition of the initial gel was: Al2O3: SiO2: H3BO4: NaOH: TEAOH: H2O = 1: 84: 5.4: 32: 9: 1900. The formed gel was transferred into a 100 mL polytetrafluoroethylene reactor, and was rotated at a speed of 15 rpm / min, and was crystallized at 150 °C for 5 days. The obtained sample was washed with deionized water until neutral, was dried at 100 °C for 10 h, and was calcined at 550 °C for 6 h to obtain a MOR molecular sieve in the form of a flake, and the relative crystallinity was 86%, and was marked as VS-1.

[0060] Comparative Example 2 Prepared according to the method in the patent embodiment 1 of CN120136124A: 1) First, 0.51 g of sodium metaaluminate and 0.40 g of sodium hydroxide were dissolved in 9 g of deionized water. After the solution was uniformly mixed, 15.75 g of silica sol (30 wt%) was slowly added to the above solution under stirring.

[0061] 2) 0.2 g of uncalcined mordenite seed crystal and 3.4 g of tetraethylammonium hydroxide (35 wt%) were added to the mixture at one time, and then the initial gel formed was continuously stirred at room temperature until uniform.

[0062] 3) The above gel was transferred into a stainless steel reactor with a polytetrafluoroethylene liner, and was crystallized at 190 °C for 12 h under dynamic conditions. The obtained solid product was separated by centrifugation, washed with deionized water until neutral, dried at 110 °C in air, and calcined at 550 °C for 4 h to obtain a mordenite zeolite powder sample.

[0063] 4) The mordenite zeolite powder obtained in 3) was exchanged with a 0.5 mol / L ammonium nitrate solution according to a solid-liquid ratio of 1:10 at 80 °C for 3 h, and the exchange was repeated twice. Ammonia was removed by calcination at 500 °C in air for 4 h to obtain a hydrogen-type mordenite zeolite, and the relative crystallinity was 93%, and was marked as VS-2 sample.

[0064] Table 1. B acid site content of eight-membered ring and twelve-membered ring of MOR molecular sieve synthesized in examples

[0065] As can be seen from Table 1, the analysis of the corresponding catalyst sample numbers VS-1 and VS-2 in Comparative Examples 1 and 2 shows that the eight-membered ring accounts for 53% to 58% of the total B acid amount, while the corresponding catalyst sample numbers HMR-1 to HMR-6 in Examples 1 to 6 are prepared by using TEAOH as the organic template and a long-chain dipiperidinium salt as the auxiliary template. In the hydrothermal synthesis, the twelve-membered ring pores are preferentially occupied due to the limitation of the molecular size, so that the Al atoms are more easily inserted into the eight-membered ring. A high crystallinity can be achieved in a short time, and the Al atoms can be controlled to be located in the eight-membered ring, so that the Al element is enriched in the eight-membered ring, the amount of B acid in the eight-membered ring is increased, and a catalyst more beneficial to the carbonylation of dimethyl ether / methanol is ultimately obtained.

[0066] Examples 7 to 14 The catalyst samples obtained in Examples 1 to 6 and Comparative Examples 1 to 2 were prepared into catalyst particles for evaluation of the dimethyl ether carbonylation reaction: 1) A fixed bed reaction tube with an inner diameter of 10 mm and a length of 530 mm was used, and the length of the reaction furnace was 400 mm. 4 g of the shaped catalyst (20-40 mesh) was loaded into the constant temperature section of the reactor, and quartz sand was loaded above and below the catalyst.

[0067] 2) The catalyst was heated according to the following programmed temperature conditions under a N2flow of 50 ml / min: room temperature for 5 h→ 360℃ for 6 h→ stop heating→ purging to reduce to 230℃.

[0068] 3) Pyridine was brought in by nitrogen, 230℃ for 3 h→ 280℃ for 3 h→ 280℃→ stop pyridine introduction. Switch to high-purity N2to purge the excess pyridine attached to the catalyst.

[0069] 4) The raw materials were a mixture of dimethyl ether (DME), carbon monoxide (CO) and hydrogen (H2), with DME / CO / H2=5 / 35 / 60 (volume ratio), the volume space velocity GHSV was 3000 mL / (gcat•h), the reaction pressure was 2.0 MPa, and the reaction starting temperature was 200℃. The reaction was carried out from top to bottom through the catalyst bed. Continuous operation was carried out, and the reaction results were detected after running for 15 h and 25 h. The gas products after the reaction were analyzed online by Agilent 7890A gas chromatograph, and the effluent of the reactor was analyzed online by gas chromatograph equipped with a thermal conductivity detector TCD and a flame ionization detector FID.

[0070] The conversion of dimethyl ether (DME) and the selectivity of methyl acetate (MA) were calculated based on the carbon molar number of dimethyl ether: Dimethyl ether conversion rate = [(carbon molar number of dimethyl ether in raw gas) - (carbon molar number of dimethyl ether in product)] ÷ (carbon molar number of dimethyl ether in raw gas) x (100%); The selectivity of methyl acetate = (2 / 3) x (the carbon molar number of methyl acetate in the product) ÷ [(the carbon molar number of dimethyl ether in the raw material gas) - (the carbon molar number of dimethyl ether in the product)] x (100%).

[0071] Table 2: Results of dimethyl ether carbonylation reaction catalyzed by H-MOR zeolite molecular sieve prepared by the method of examples and comparative examples

[0072] As can be seen from Table 2, the conversion rate of dimethyl ether carbonylation reaction of the MOR molecular sieve catalyst prepared by the method of examples provided by the present application is more than 50% (TOS=50h), and the selectivity of methyl acetate is >99%; while the conversion rate and the selectivity of methyl acetate of the catalyst VS-1 and VS-2 prepared by the method of comparative examples are <35% and <98% respectively at TOS=50h. This shows that the catalyst provided by the present application has good catalytic activity and selectivity of dimethyl ether carbonylation reaction to generate methyl acetate.

[0073] The conversion rate of dimethyl ether carbonylation and the selectivity of methyl acetate of the MOR zeolite molecular sieve catalyst prepared by the method of examples provided by the present application are >45% and >99% respectively at TOS=100h, while the conversion rate and the selectivity of methyl acetate of the catalyst VS-1 and VS-2 prepared by the method of comparative examples are <33% and <97.5% respectively at TOS=100h. The conversion rate of dimethyl ether carbonylation and the selectivity of methyl acetate are >41% and >99% respectively at TOS=200h, while the conversion rate and the selectivity of methyl acetate of the catalyst VS-1 and VS-2 prepared by the method of comparative examples are <31% and <97.0% respectively at TOS=200h. This shows that the catalyst provided by the present application has good catalytic activity and deactivation resistance.

[0074] The above is only a few embodiments of the present application, and does not limit the present application in any form. Although the present application is disclosed with preferred embodiments, it is not intended to limit the present application. Any skilled person in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present application, which are equivalent to equivalent embodiments, and all belong to the scope of the technical solution.

Claims

1. A method for synthesizing H-type high-silica sheet-like MOR zeolite molecular sieves, characterized in that, The synthesis method includes: (1) Add an aluminum source to a mixed solution containing an alkali source, tetraethylammonium hydroxide, long-chain bispiperidine onium salt and water to form a slurry, add a silicon source and small-crystal MOR zeolite molecular sieve seed crystals to the slurry, and mix evenly to obtain a silica-alumina sol. (2) After aging the silica-alumina sol, a crystallization synthesis reaction is carried out. The crystallized product is subjected to ammonium ion exchange, filtered, washed, dried and calcined to obtain H-type high silica sheet MOR zeolite molecular sieve.

2. The synthesis method according to claim 1, characterized in that, The long-chain bispiperidine onium salt is selected from at least one of 1,1'-(1,6-hexadiyl)bis[1-methyl-diiodopiperidine onium], 1,1'-(oxadi-2,1-ethylenediyl)bis[1-ethyl-dibromopiperidine onium], 1,1'-(thio-2,1-ethylenediyl)bis[1-methyl-dichloropiperidine onium], 1,1'-(1,10-decadiyl)bis[1-methyl-diiodopiperidine onium], and 1,1'-[1,4-phenylenebis(methylene)]bis[1-ethyl-dibromopiperidine onium].

3. The synthesis method according to claim 1 or 2, characterized in that, In the silica-alumina sol, the alkali source is calculated as Na2O, the silicon source as SiO2, the aluminum source as Al2O3, the tetraethylammonium hydroxide as TEA2O, and the long-chain bispiperidine onium salt as PIPD. The molar ratio of each component is 0.04~0.15 Na2O:SiO2:0.02~0.08 Al2O3:0.01~0.5 TEA2O:0.02~0.25 PIPD:8~40 H2O. The amount of small-crystal MOR zeolite molecular sieve seed crystals added is 1wt%~10wt% of the mass of SiO2, preferably 1wt%~5wt%.

4. The synthesis method according to any one of claims 1 to 3, characterized in that, The aging process is carried out at a temperature of 40~130℃, preferably 80~120℃, and the aging process is carried out for a time of 12~72 hours, preferably 12~48 hours. And / or, the temperature of the crystallization synthesis reaction is 140~200℃, preferably 180~200℃, and the time of the crystallization synthesis reaction is 12~72 hours, preferably 12~48 hours; And / or, the slurry after the crystallization synthesis reaction is washed with water until the pH is 7-8, dried at 100-120℃ for 4-12 hours, and then calcined at 450-650℃ for 4-12 hours at a heating rate of 1-5℃ / min to obtain molecular sieve raw powder.

5. The synthesis method according to any one of claims 1 to 4, characterized in that, The ammonium exchange involves exchanging calcined molecular sieve powder with a soluble ammonium salt aqueous solution at 60-90°C at a solid-liquid mass ratio of 1:(5-30) for 1-6 hours, and repeating the exchange 1-3 times. The concentration of the soluble ammonium salt aqueous solution is 0.1~1.0 mol / L, and the soluble ammonium salt is selected from at least one of ammonium nitrate, ammonium chloride and ammonium sulfate, ammonium carbonate, ammonium bicarbonate and ammonium acetate.

6. The synthesis method according to any one of claims 1 to 5, characterized in that, After ammonium exchange, the mixture is dried and calcined. The drying temperature is 80~150℃ and the time is 2~24 hours. The calcination temperature is 450~600℃ and the time is 1~12 hours.

7. The synthesis method according to any one of claims 1 to 6, characterized in that, The silicon source is selected from at least one of silica sol, water glass, silica gel, type C silica gel, fumed silica, chromatography silica gel, methyl orthosilicate, and tetraethyl orthosilicate; the aluminum source is selected from at least one of sodium aluminate, sodium aluminate, aluminum hydroxide, boehmite, aluminum nitrate, aluminum chloride, aluminum powder, aluminum isopropoxide, and aluminum sulfate; the alkali source is selected from at least one of NaOH, Na2O, Na2O2, Na2CO3, and metallic Na.

8. An H-type high-silica sheet-like MOR zeolite molecular sieve prepared by the synthesis method according to any one of claims 1 to 7, characterized in that, The Si / Al molar ratio of the H-type high-silica sheet-like MOR zeolite molecular sieve is 30:1~5:1, preferably 20:1~7:1; the thickness of the H-type high-silica sheet-like MOR zeolite molecular sieve in the c-axis direction is <200nm, preferably ≤100nm.

9. The application of the H-type high-silica sheet-like MOR zeolite molecular sieve of claim 8 in the carbonylation reaction to prepare methyl acetate, characterized in that: Methanol carbonylation can be carried out using methanol and carbon monoxide, or dimethyl ether carbonylation can be carried out using dimethyl ether and carbon monoxide.

10. The application according to claim 9, characterized in that, Methyl acetate is synthesized by reacting a feed gas containing dimethyl ether, carbon monoxide, and hydrogen through a catalyst bed supported by H-type high-silica sheet-like MOR zeolite molecular sieves. The reaction temperature is 180~280℃, preferably 180~240℃, the reaction pressure is 0.5~6.0 MPa, preferably 2.0~5.0 MPa, and the gas hourly space velocity is 1000~6000 mL / (gcat•h), preferably 1500~4000 mL / (gcat•h). The molar ratio of dimethyl ether, carbon monoxide and hydrogen in the raw gas is 1:(4~10):(3~15), and a dry inert gas is used as the pretreatment gas.

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